The present invention relates to an archery arrow composed of graphite (carbon) with the carbon fibers running in two mutually, substantially perpendicular directions on the arrow shaft. In addition, the arrow shaft is partially tapered and partially non-tapered.
The earliest known archery arrows were made of wood, usually cedar. These arrows had a number of disadvantages. First, they warped when exposed to moisture. As a result of this warping they were not straight and therefore did not fly straight when released from the bow. In addition, they were quite fragile and broke when they hit a hard object. Furthermore, they did not have sufficient kinetic energy to penetrate targets such as large game animals.
The kinetic energy of an arrow in flight may be calculated according to the formula: ##EQU1##
The disadvantages of wood arrows led to the development of aluminum tubular arrows. These arrows were about 25% lighter than cedar wood arrows and therefore flew faster (about 220 ft/sec), developing more kinetic energy because kinetic energy is related to the square of the velocity. They were also straighter than cedar arrows and did not have a tendency to warp. They were straight throughout the length of the shaft and did not taper.
However, aluminum arrows have a tendency to bend rather than break when they hit a hard object. It can be quite difficult to straighten the arrow after it has been bent.
More recently, carbon (graphite) arrows have been developed. Graphite arrows are constructed from carbon fibers that are pulled off a spool and through a die with eyelets, then through a smaller die and through a bath of polyvinyl or polyester resin and onto a mandrel for curing. After being placed on the mandrel, the carbon fibers and resin are heated to cure them. The cured product is then removed from the mandrel and cut to appropriate lengths for individual arrows. These arrows also generally had parallel walls (no taper).
These graphite arrows were lighter and tougher than aluminum, and do not bend when striking a hard object. The lighter weight lets them fly faster, developing higher kinetic energy.
These arrows also had a number of disadvantages. The production process left a mold release on the outside of the resin which was quite slippery. In order to fletch such arrows (put the vanes on), the arrows had to be sanded. Furthermore, it was quite difficult to tune these arrows for use with a fixed blade broadhead tip.
To address some of these problems, some manufacturers such as Taylor Falcon, Jonesboro, Ark. developed carbon arrows with a continuous taper throughout the length of the shaft. However, these arrows did not have commercial success because the sizings were wrong, the weights were inconsistent, and a dealer had to have many different diammeter tools to mount tips to the shaft. That is, depending at the point along the taper where the material was cut to length, a different outside diameter of the shaft resulted and a different tool was needed to mount the tip. Furthermore, most of these arrows were constructed of unidirectional fibers, with the fibers runninig lengthwise along the shaft. There was thus no bracing across the shaft diameter, so that these arrows were relatively fragile. In addition, these arrows tended to have a longer "paradox" or oscillation along the shaft which caused inaccuracy in flight and less penetration after hitting a game animal. Furthermore, they had a relatively limited "spine weight" range of stiffness, so that it was difficult to use them with heavier bow strengths (greater than 70 pounds). Crisscrossing or biasing of fibers has been tried.
There is a need for an improved graphite archery arrow that retains the advantages of tapered arrows while solving the problems of tapered arrows and correcting the problems with graphite arrows with no bias.